Looking at the region_block code, particles are determined to be inside
the block region based on the xlo, xhi, etc. values for the block
region. Does this assume that the blocks are oriented along the
coordinate axes? If I rotate a block by 45 degrees, being inside the
xlo, xhi, etc. values does not necessarily put the particle in the box,
right? Or do you instead rotate the particle coordinates in the
opposite direcition to determe if it is inside?